This invention relates to glass-ceramic capacitors having buried base-metal electrodes and more particularly to such a capacitor having a reduction resistant high Q glass-magnesium titanate body with copper electrodes.
Magnesium titanate has been used as a capacitor dielectric providing a low dielectric constant (K), a low or smooth temperature coefficient of capacity (TCC) and a high quality factor (Q). The Q of a capacitor is defined as the ratio of capacitive reactance to equivalent series resistance at the frequency of measurement.
It is also known to combine a magnesium titanate powder in a glass and provide copper containing electrodes to form cross-overs in a multilayer printed circuit or a capacitor on an alumina substrate. However, no more than 25 weight percent magnesium titanate is prescribed for use in the glass-ceramic body and at least 75% glass is employed toward matching the thermal coefficient of expansion of the alumina substrate, and these materials provide 1 MHz values of Q in the range of 400 to about 800.
It is an object of the present invention to provide a low cost monolithic capacitor including a low firing magnesium titanate body exhibiting a high Q at 1 MHz.